New Born Network

hello,
well im am at it again,i have a project to do that could prove either to be very difficult or very elemtary. i haven’t the foggiest what equiptment i will need other than NIC cards, CAT5 wiring and swithches. i don’t even know what OS would be the best to defeat this beast, if anyone out there has any steps to go about designing this monster let me know. thanks always

FIRST: i need to network 70 pc’s together
SECOND: i need to connect to a email intrAnet
THIRD: i need to connectto the internet via a DSL connection